Dose response curves for prostaglandin F2 alpha (PGF2 alpha), estradiol and LH are to be determined in dissociated cell preparation of bovine corpora lutea collected at day 12 of the estrous cycle. The endpoint will be progesterone accumulations. Minimally effective levels of estradiol and PGF2 alpha will be added in combination in the absence and presence of LH to evaluate a potential luteolytic interaction and the corpus lutuem as a site of action of estradiol. Effects of PGF2 alpha alone and in combination with estradiol on progesterone accumulation are to be evaluated at different stages of the estrous cycle. A dissociated cell preparation of bovine ovarian follicles is to be developed. Products of these incubations are to be added to dissociated cell preparations in the presence and in the absence of PGF2 alpha to evaluate a luteolytic interaction between follicles and PGF2 alpha. Preliminary studies suggested metabolites of PGF2 alpha have an influence on effects of PGF2 alpha in the dissociated cell preparation. The metabolism of H3-PGF2 alpha will therefore be investigated and in parallel incubation the mass of metabolites of PGF2 alpha determined by RIA. The effects of metabolites of PGF2 alpha on progesterone accumulation will be determined. BIBLIOGRAPHIC REFERENCES: Hixon, J.E. and W. Hansel. 1974. Evidence for preferential transfer of prostaglandin F2 alpha to the ovarian artery following intrauterine administration in cattle. Biol. Reprod. 11:543-552. F2 alpha to cause luteal regression in ewes after destruction of ovarian follicles by X-irradiation. Biol. Reproduc. 13:125-135.